GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"2409 results found.
- GRB 250329B: SVOM detection of a faint transient
- GRB 250329A: Swift-XRT afterglow detection
- GRB 250328A: SVOM/VT optical observation
- GRB 250329A: Fading optical counterpart detection by LCO.
- GRB 250328A: SVOM/C-GFT optical upper limit
- GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
- GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
- GRB 250329A: VLT/X-shooter redshift z = 2.921
- GRB 250329A: SVOM/VT optical counterpart confirmation
- GRB 250329A: SVOM detection of a burst
- GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
- GRB 250327B: MASTER detection of OT rebrightening
- GRB 250327B: LCO optical counterpart detection
- GRB 250328A: GWAC-F50A optical upper limit
- GRB 250328A: SVOM detection of a burst
- GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
- GRB 250327B: further optical observations by LCOGT
- GRB 250327A: SVOM/VT upper limits on the XRT position
- GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
- GRB 250327B: Las Cumbres optical counterpart detection
- GRB 250327B: Swift-XRT detection of the X-ray afterglow
- GRB 250327B: 1.6m Mephisto optical observations
- GRB 250327B: NOT spectroscopic redshift z = 3.035
- GRB 250327B: GOTO optical counterpart detection
- GRB 250327B: SVOM/VT optically bright counterpart
- GRB 250327B: SAO RAS optical candidate
- GRB 250327B: SVOM detection of a burst
- GRB 250327A: J-band observations with WINTER
- GRB 250327A: SVOM/VT optical candidate
- GRB 250321B: Swift-XRT observations
- SVOM/sb25032302: SVOM detection of a long X-ray transient
- GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
- GRB 250225B: GECAM-A detection
- GRB 250321B: Swift ToO observations
- GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
- GRB 250320B: Fermi GBM Observation
- GRB 250320B: Fermi-LAT detection
- GRB 250321B: SVOM detection of a sub-threshold transient event
- EP250321a: SVOM/VT optical observation
- GRB 250320B: SVOM/GRM observation of a long burst
- GRB 250314A: Keck/NIRC2 J-band upper limit
- GRB 250313A: GRBAlpha detection
- GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
- GRB 250317C: SVOM/GRM observation of a long burst
- GRB 250317B: Leavitt Observatory optical upper limit
- GRB 250317B: GTC/OSIRIS+ spectroscopic redshift z=3.44
- GRB 250317B: REM optical/NIR observations
- GRB 250317B: Swift-XRT observations
- GRB 250314A: REM optical/NIR upper limits
- EP 250317B: Fading optical counterpart detection by LCO
- GRB 250317B: LCO detection of the fading optical afterglow
- GRB 250317B: refined SVOM/MXT analysis
- GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
- GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
- GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
- GRB 250317B: SVOM detection of a burst
- GRB 250314A: SVOM/GRM analysis
- GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
- GRB 250314A: EP-FXT afterglow detection
- GRB 250314A: Swift/UVOT Upper Limits
- GRB 250314A: Swift XRT Detection
- GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
- SVOM/MXT upper limit on GRB 250314A
- GRB 250314A: SVOM/VT upper limit
- GRB 250314A: NOT near-infrared candidate counterpart
- GRB 250313A: Fermi GBM Detection
- GRB 250313A: CALET Gamma-Ray Burst Monitor detection
- GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
- Konus-Wind detection of GRB 250313A
- Konus-Wind detection of GRB 250308A
- GRB 250314A: SVOM detection of a burst
- GRB 250313B: SVOM/GRM observation of a soft bright short burst
- GRB 250313A: SVOM/GRM observation of a bright long burst
- EP250304a: SVOM/VT optical observation
- GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
- GRB 250308A: CALET Gamma-Ray Burst Monitor detection
- GRB 250311B: SVOM detection of a burst
- GRB 250309B: SVOM/VT optical observation
- IPN triangulation of GRB 250308A (short)
- GRB 250308A: SVOM/GRM detection of QPO in the tail emission
- GRB 250308A: SVOM/GRM observation of a bright short burst
- GRB 250305A: AstroSat CZTI detection
- GRB 250305A: SVOM/GRM observation of a burst
- GRB 250219A: SVOM/C-GFT optical upper limit at early phase
- Konus-Wind detection of GRB 250222A
- IPN triangulation of GRB 250222A
- EP250302a: SVOM/VT optical observation
- EP250302a: Xinglong F60B optical observation
- EP250302a: SVOM/C-GFT optical observations
- GRB 250225B: EIRSAT-1 GMOD Detection
- GRB 250226A: Fermi GBM Observation
- GRB 250225B: INTEGRAL SPI-ACS detection
- EP250226a / GRB 250226A: SVOM/VT optical observations
- LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
- GRB 250225B: REM NIR upper limits
- Konus-Wind detection of GRB 250225B
- GRB 250225B: SVOM/GRM observation of a long burst
- GRB 250214A: SVOM/GRM observation
- GRB 250223C: SVOM/GRM observation of a long burst
- GRB 250219A: EP-FXT afterglow detection